The overall objectives of the study are to determine the incidence and degree of abnormal retinal capillary permeability by vitreous fluorophotometry (VFP) and of abnormal glomerular permeability to protein following exercise in persons 12-22 years of age who became insulin-dependent before the age of 16. The findings will be correlated with age, duration of diabetes, clinical findings, degree of control, with pulse, blood pressure, and EKG readings at rest and during exercise. Yearly studies will determine the natural history of capillary permeability in these two sites and permit ascertainment of whether abnormal permeability is predictive of morphologic changes. It will provide a data base for evaluation of drug therapies in which changes in permeability will serve as indices of drug effectiveness.